Oecumenius

Who made him heir? Over whom? Over all things. Of all who approach the immortal and divine nature.Indeed, the Son is the heir and participant of the Father's substance [οὐσίας], wealth, and power. Then, when he said that the Son is the heir of the Father's possessions, he also explains how. Through him, he says, the ages were created: that is, the ages are the common works of him and the Father. But if the ages are the mutual work of the Father and the Son, then those things which are in the ages are certainly mutual to the Father and the Son. And if those things which are in the ages, much more those things which are after the ages, namely the world and those things which are in it.
Then, lest you think that the heir is not called an heir by nature, but by a certain grace and adoption, Paul adds: “He is the radiance of His glory,” saying practically: Although I have said that the Father appointed him as heir, understand that nothing humble or unworthy of God is implied. For it is not said that the heir is to be made by the act of adoption and that he is to be considered as such, but rather it is a declaration of the relationship of the Son to the Father as a cause according to nature of reference and consent: and lest you think the Son exists without a principle, alienating him from the paternal kinship, and imply two principles separated from each other. Indeed, for this very reason he was also called by me heir, so that you may immediately understand from whom the inheritance descends, nor may you suspect him to be unbegotten like the Father: for this reason it was said by me, Heir, and, He appointed. Therefore, I immediately added: Who, being the radiance.
But if it is not established that there was or would be radiance (for Paul says: when there was radiance), nor is the heir truly appointed, but only in the way I mentioned above. But see how significantly and precisely he has spoken, when he says Radiance, having said a representation, and being, and of the glory. For by radiance, he reveals the natural progression [πρόοδον] of the Son from the Father.
Indeed, the radiance of anyone never proceeds entirely through grace or adoption, neither from the sun, nor from fire, nor from any other source from which radiance is usually derived. However, by saying "he is," he shows that this is not something newly made for him to be radiance, but that it has always been from eternity.
For who is [ὤν], since He does not have a recent existence but is from eternity and always is. Then also the divine attribute is presented through who is. For thus also the Father says, "I am the the One who is [Ἐγώ εἰμι ὁ ὢν]," speaking to Moses (Ex. 3:14).
Therefore, there are testimonies to demonstrate both the natural progression of the Son from the Father and the consubstantiality [ὁμοούσιον], and coeternal [συναΐδιον], as well as what he says: "The Radiance," and what he states: "who is." Indeed, he also adds "of his Glory," so that you may say: "His radiance is the Son," which is most honorable, and it comes from nature, and there is nothing greater in the Father.
You see how and whose heir the Son is? Then, explaining more clearly what has been said, Paul adds: "and the exact representation of His being." That is, having embraced the essence and substance in Himself, God is of infinite authority, omnipotent, Creator, and whatever else expresses the being of the Father, besides being the Father, all these things are the Son: therefore, He encompasses and sustains all things by His powerful word, and governs them.
Do you know how he is truly the heir and sustains all that belongs to the Father? Afterwards, when Paul spoke of the divine and supernatural about the Son, he also transitions to the rest: which are most admirable and no less supernatural, yet by hearing they seem humble and lowly, for example, death and killing! But…………………………………………………….
"through whom also He made the ages.” Where are those who say, “when the Son was not”? For the Creator of the ages is not subject to time. But since the Father is the cause of the Son, it is fitting that He is also the cause of those things that came into being through Him. Therefore he says: through whom. For the Father seems to act when He begets the Son who has done these things.
"He is." It is called a radiance, indicating the manner in which it originates from the Father, as if in some way it is an outward procession, neither entirely freed from the source of its existence, nor entirely constituted, but rather emerging, as if to stand by itself, and to have its own existence. Thus, the holy Cyril in the fifth book On the Trinity. The manifestation of the consubstantial and coeternal, as light from light. The character, as the likeness of the glory, is the Son of the Father. For the Son of the Father is similar and unchangeable, and as if into a character in different being [ὑποστάσεσι].
"sustaining all things." As if carrying the invisible and the visible in the word, bearing and governing. And he said word [Ῥῆμα], showing that he easily leads and carries all things.

The Epistle to the Hebrews indeed seems not to be from Paul, both because of the style of writing and because it does not attach his name, as in all the other Epistles; also because it says: "How shall we escape if we neglect so great a salvation, which at first began to be spoken by the Lord, and was confirmed to us by those who heard Him, God also bearing witness with signs and wonders?" (Heb. 2:3-4) And indeed the reason why the style was changed is evident. For it is said to have been written to the Hebrews in their own language, later translated, as some think, by Luke, but as it seems to most, by Clement; for he also preserves its character.However, the reason why he did not attach his name to the Epistle is the order of the matter. For Paul was the apostle of the Gentiles, and not of the Jews. For he had given the right hand of fellowship to Peter and the other apostles, so that he himself would minister among the Gentiles with Barnabas, while those around Peter would go to the circumcision. Since there was a partnership in preaching, and the Jews had heard that Paul was teaching a departure from the law, it is fitting that he writes a letter to the Hebrews to show the agreement of the preaching. However, when he was writing to them, it was not appropriate for him to declare himself an Apostle at the beginning. The letter itself also testifies that it is Paul's, as it says: You have also shared in the afflictions that have come upon me in my chains. (Heb. 10:34) And when he says: "Pray more earnestly that I may be restored to you more quickly" (Heb. 13:19); furthermore, when he says: "You know our brother Timothy has been released, with whom, if he comes soon, I will see you." (Heb. 13:23) For no one except Paul, as I believe, had sent Timothy into ministry: and while waiting for him more quickly, he promises them his own and Timothy's arrival, as he often does. Many other things also show us that this is his Epistle, as the reading itself teaches in the course of it.

For what reason does Paul, being the Apostle to the Gentiles, write to the Hebrews? And this while they were hostile towards him because he was paralyzing [παραλύειν] the law? For Peter and the others who were with him, lowering themselves to the weak understanding of the Jews, were somewhat following the law. We say that just as it was not committed to Paul to baptize, yet out of an abundance of ministry he was also baptizing: so he writes to the Hebrews, although he was sent to the Gentiles. Indeed, he had anxious care for them, so much so that he even said: "I could wish to be accursed from Christ for their sake" (Rom. 9:3); and again: "I am going to Jerusalem to minister to the saints." (Rom. 15:25) Therefore, Paul writes to those who had already believed in Jerusalem and in Palestine: he writes, however, to comfort them because they had suffered many afflictions from their own fellow countrymen who did not believe, as he himself indicates, saying, "Strengthen your limp hands and your weak knees." (Heb. 12:12)
However, two points in this in the Epistle: Paul comforts them that they have bravely endured temptations, and that a good reward will be given for these things. Moreover, he discusses many things about faith, showing that the Jewish practices are no longer necessary, as it was a figure of the truth,while our own practices are necessary as they are the truth.
Therefore, why Paul did not add a proper name when writing to the Hebrews, Clement writes in his "The Hypotyposes" as follows: Now indeed, as the blessed elder says: When the Lord was sent as the apostle of the Almighty God to the Hebrews, it was done out of modesty that Paul, who was sent to the Gentiles, did not write himself as the apostle of the Hebrews, out of honor bestowed upon the Lord. Furthermore, out of abundant love, it was done that the preacher and apostle of the Gentiles also wrote to the Hebrews.

Paul writes this from Italy. The occasion of the letter was this. Since the Jews were insisting on the law and shadowy figures, the apostle Paul, having become the teacher of the Gentiles and sent to preach the Gospel to the nations, wrote this letter after he had written to all the Gentiles, also to the Hebrews who had believed from the circumcision, to teach them through this Epistle, in which he declares that Christ has come and that the shadow of the law has ceased. And indeed, it first demonstrates that prophets and announcers [μηνυτὰς] of his coming were sent for this reason, and that Christ himself is the Son of God, through whom all things were made. And that this Son had to become a man, so that by the sacrifice of his body he might destroy death. For salvation was to come to all not through the blood of calves or goats, but through the blood of Christ. Moreover, it shows that the law made no one perfect but had only a shadow of the good things to come. The Jewish people did not find rest, but a day of rest was left to all of us in common. Furthermore, it also demonstrates that the priestly ministry was transferred from Aaron to Christ: whose figure was Melchizedek, who was not descended from Levi. It signifies that the fathers were justified by faith, and not by the works of the law. Then, after Paul also urged them to have good morals and praised their tolerance for Christ, and advised them to honor the elders, he concludes the Epistle.

The inheritance primarily belongs to those who are entitled, but not to those who are alienated. Thus, what was fitting for the heavenly Word was received below through the flesh that was also assumed. But what is that? The Son, of the God of all, who is also the Father of that flesh, is to say, "I have begotten you." (Ps. 2:7) What he says: "today" is not a sign of time, but that the Father has never been separated from the legitimate paternal relationship that He has with the Son.
But if he were to say: I have always been affected towards you in this way: not as if a generation has come, but that it may always persist and continuously derive a beginning, with no end. Indeed, consider whether it may be adapted in such a way that both are indeed said of Christ, namely, "You are my Son," and "Today I have begotten you" (Ps. 2:7): but that, "You are my Son," insofar as He is the Word: for it signifies His eternal birth; whereas "Today I have begotten you" refers to the flesh: for it designates a recent birth. For He was born by the good pleasure of the Father."The Holy Spirit,” said the angel, “will come upon you”; and then also: “The power of the Most High will overshadow you." (Luke 1:35)